1. Technical Field
The present invention relates to an optical position detection device and a display device with a position detection function capable of optically detecting a position of an object matter in a detection area.
2. Related Art
For electronic devices such as cellular phones, car navigation systems, personal computers, ticket-vending machines, or banking terminals, there are used in recent years display devices with a position detection function each having a touch panel disposed on the front of an image generation device such as a liquid crystal device, and in such display devices with a position detection function, information is input with reference to an image displayed on the image generation device. Such touch panels are each configured as a position detection device for detecting a position of an object matter in a detection area (see, e.g., FIG. 6 of JP-A-2001-142643).
The position detection device described in the document mentioned above is of an optical type, and has a configuration of setting a detection area on the side of the display surface for displaying an image in the direct view display device, and having a plurality of light emitting diodes and a plurality of photo transistors disposed on both sides across the detection area. In such a position detection device, if the object matter enters inside the detection area, the light is blocked by the object matter, and therefore, by identifying the photo transistors the light to which is blocked, the position of the object matter can be detected.
However, in the optical position detection device described in the document mentioned above, it is required to dispose a number of light emitting diodes and the photo transistors corresponding to the resolution of the position coordinate to be detected around the detection area, which is impracticable.